The new league year has begun and many NBA teams are in desperate need of bringing in a player that will improve their squad.

Certain teams, like the Brooklyn Nets, have gotten significantly better since the season ended. The Nets acquired sharp-shooting Joe Johnson, along with the promise to sign an extension from Deron Williams.

The nature of sports is that while one team is winning, another has to be losing.

William's decision to stay with the Nets disappointed the Dallas Mavericks and their fans, who had put so much hope in luring the talented point guard back to his hometown.

With the draft behind us, teams now have to focus on free agency to improve. Although there are plenty of talented free agents on the market this year, it doesn't even begin to compare to the 2010 free-agent class.

Few players that are available will change the future of a franchise, but quite a few players could greatly enhance many teams across the league.

Here are a handful of teams that are in need of signing a difference-maker.

Dallas Mavericks

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After winning last year's NBA title, the Dallas Mavericks allowed some of their key contributors move on to other teams rather than overpay for their services.

The thought was that the Mavericks would save cap room for this summer to sign either Deron Williams or Dwight Howard. As it happened, Howard signed away his opt-out option and Williams has decided to sign an extension with the Brooklyn Nets.

Currently, the Mavericks have plenty of cap room but no one on the market is worthy of big money.

The Oklahoma City Thunder swept the Mavericks in this year's playoffs and it was clear that the Mavs needed to get Nowitzki a lot of help and quickly.

In the past year, the Mavericks have seen Tyson Chandler, J J Barea, Jason Kidd and Jason Terry leave in free agency. At this point, the Mavericks look like they are in a lot of trouble and it looks like a playoff berth isn't a guarantee for them next season.

Nowitzki isn't getting any younger so the Mavs need to put together a competitive team together sooner rather than later.

After missing out on both Williams and Jason Kidd in free agency, the Mavericks need to focus on signing a point guard to fill that void.

What Dallas will do is unknown, but at this point, it appears as if they should be really desperate to make something happen in free agency.

Houston Rockets

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The Houston Rockets have been very busy thus far this offseason. Gone are Kyle Lowry, Samuel Dalembert, Goran Dragic and Chase Budinger but they are still without the superstar they have chasing over the past year.

Since Yao Ming retired, the Rockets have lacked a player that could be the face of their franchise. They thought they had landed Pau Gasol prior to last season, but the trade was vetoed by NBA commissioner David Stern.

In this year's draft, the Rockets loaded up on young talent as they had three first-round draft picks. With those picks, they took shooting guard Jeremy Lamb, point-forward Royce White and Terrance Jones, who was a member of Kentucky's NCAA championship team.

Since the new league year began, the Rockets have made large offers to restricted free agents Omer Asik and Jeremy Lin. Although, most experts believe that neither player will wind up playing for the Rockets next season as the players' old teams are expected to match the offers.

Next year's version of the Rockets will be different than the one that missed the playoffs this year. The current roster has many questions facing it like, who is going to play point guard? It is surprising that the Rockets have such a void at point guard considering that the team had both Lowry and Dragic at last season's conclusion.

It doesn't appear that the Rockets can do any more this offseason, other than trading for perennial All-Star Dwight Howard.

Houston GM Daryl Morey has proven that he will do whatever he deems to be right to put a winning team on the court, the question is how much longer it will take him to build a roster with a chance to be successful.

Charlotte Bobcats

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As everyone knows, last season's Charlotte Bobcats had the worst winning percentage in league history.

So far this offseason, the Bobcats added Michael Kidd-Gilchrist with the second pick of the draft. While Kidd-Gilchrist promises to bring much needed energy and defense, he isn't expected to create much offense. The problem with that is that the Bobcats finished dead last in scoring last season and need someone to come in and help solve that problem.

The Bobcats making a play for Antawn Jamison could make a lot of sense. Like every NBA player, he is is looking to paid more than he is worth. It may make sense for the Bobcats to slightly overpay on a short-term contract because Jamison would help make the team more competitive on a nightly basis.

No one is expecting the Bobcats to contend for a playoff spot next season, but they have to show some improvement on last season's horrific performance.